Relief valve



March 12, 1935., R. w. MOLAUGHLIN RELIEF VALVE Filed May 29, 193s 0rfa/Ve III A20-f) FEI/Ve open/'lig InveT-fOP. R Weg-1e Mc; Loughlin,

H15 mmv-leg All Patented Mar..12, 1935 in STATES RELKEF VALVE 1R.' Waynei McLaughlin,

General ,Electric Company, a .-col'nrationtof 4-New York YVApplicationMay 29,

6 Claims.

y@'I'lfle.rlresentinvention.relates to relief valves sfor. relievingv yafluid under` fluctuating f pressure avhen-thepressure-reaches orexceedsa predeter- ...mined .value y Y Therordinary relief .valvecomprises a.movable (valve. member and-aspr-ing for biasing the valve membertowards its: seat. Such 'a valve has a positive .regulation` thatv is,Va gradual increase .-nA pressure :isrequired to move the valve mem-.ber-awayirom its seat. Or, from another viewpoint, such avvalve doesnot permit the pressure .to-be relievedhtobe .maintained constant but .Keffects an increase inpressure in response to the opening travelof thevalve. Ylf"urthermore,.the movablevmember `of such -a relier valve hasva l,tendency to-,v-ibrate if there is some disturbance 4inr the-iluidpressure,.particularly When themov- #fablevalveQmember-is riding nearits-seat.

'l `Oneobject of -myvinvention is to yprovide an ,i improved structureland arrangement of relief vvalve fwherebyany desirable regulation ofthe valve may be obtained, and particularly whereby aKconstantipressurein a container may be mainv,-tainedirrespective of theposition'of the movable memben ofthe reliefvalve. This is accomplished A.in-.accordancewith my invention by the provision .O fumeansbasing .themovable valve member towards itsseatwith a forcedecreasing in responseto .the Vopening vtravel of the .movable valve imernben` Forf..a,betterunderstanding of What`I` believe .-.to..be ,novel and myinvention,attention is directed to. thefollowing description andthe claims...appended theretoin.connection-With the accompanyirlg drawing.

In the.,drawing-,.Fig. 1V represents a valve struc- .tureembodying myinvention; Figs.'2 to 5 are `explanatory.illustrations; and Figs. Gand 7represent Lmodiiications of my invention.

Thevalve structure shown in Fig. 1v comprises a casing `10 having a,flangedportion ll dening .faninlet and. another .anged portion .12vdening Y ..an.outlet. The lr'langeclportion,11 is fastened to .aVflanged conduit portion 13V by means of bolts 11,4.. TheAVfiangedportion .13 may form a part of La,c0nd11t,.a-drumforlikelcontainer for containing lfluid;,underpressure A ring memberl definingMayalve:seat isiastened to the inlet portion by :a weldgldthusorming apart of :the valve casing. .A cover ,1'7A isiastened` to.. anotheryflanged portion y 11,l8.of,the..casing.by meansof bolts A19. The coverylYLdelnes .af.seat.20.for.a stem 21. The. latter has an upper threadedportion 22 engaging a threadzedtportornof,..a.,cap.23y .which has a4face-bearing .againstthe cover ,17. It.yvill.be readily seen thattturn-ingaoftlthe. cap.f23. on the` stem21 causes .the`.attento.travelnpward so .thata `collar 24: of the :Stem..is,.,for,cedV towardsv the, seat `20 Uoi the, cover :17. @,'Ihelatter,ist provided-.with channels ...25, '26

aaclosedrbyz asplilg'l .,for., draining Vfluid leaking i933, semina.673,448

(cram-nit) pastthe seat .20` andthe collar 24r into the. cap.23. Anintermediate portion,28 ofthe Vstern isfscrewthreaded for holding .anadjustableV spring .platef29- The movable member 30 oftlie'valveinaccordancewith my invention comprises a cylini" dricalmember vSlislidablyarranged on the lower end oi the stem, and a bottomplate or disk 32. This vmovable.member,30 as .will .be readilyseen fromthedrawingdeflnes Withthestem achamber 33 which ,communicateswiththeilet ,off` the valve through openings 342m theldi'sk. A :Spring 35concentrically ,arranged with ,the cylindrical portion of .the movable-membe1.,a.nd the ste,m..is

held .between the disk of theV movable memberV andthe spring plate 29..'Ifhespring is under compression which may be adjusted. by v turningthe. spring, plate ,onthe screw-threaded portion .of thestemandthespriiigbiases. the movable member tovva'rdsits seat. ,Apinlprojectingthrough it will be seenthat the lforce acting onthelovverside of the, Vvalve is determined by theA pressure P1 and by the-area'Ai on vvhichpthepressureacts andi is equaltothegproduct 'AiXPrrepresented 'by thel area abcd.

In FigLB `I have-shown the movable `valve ,member moved away `from itsVseatso that'iluid under pressure may flow throughthe Vopening definedVbetweenV the movablememberand the seat. iiow -of uid' causes ya'conversion ofV theV potential energyof the fluid into" kineticorlvelocity energy,V

to thev effect that thepressure near-'the edge of Vther movablememberYdecreases. Intthis case 'the force acting `on the '--lowerside of Y the-movable member fmayVv be -expresse'df as lthe product Aof AiXPiXi,reperesented'by the'are afarbicidi,` f`

representing a factor-equal ito the'ratio aibicici abcd in whichalbicidirepresents the areashownin Fig. 3 andabcd' the. area.` indicated in.Eig..2. .The vfactor f depends ,upon t1'le., iovvand -therefore l maybe termedajlow actor. ,.'Ifhegforce .acting on the (loWer .side .of .the,movable :.member. decreases l in .response to' the opening. travel; Theforce is` represented bythe product AiPif, in which f is `unityatqclosed ,positionbf ,the .yalveand ,decreases .as .the valve opens,napproaching .-zero .,20 abore inthe stem andscrewfthreaded to the* Thiszero value, however, is not reached in actual relief valve designs. Thechange of the ilow factor in response to the valve opening is shown inFig. 4.

In order to keep the valve opened in any position at a constant pressureP1 it is necessary to apply a biasing force on the upper side of thevalve, which decreases in accordance with the decrease of themagnitudeof .the iowrfactor.Y

The force biasing the movablemember towards its seat in the structureaccording to my invention may be represented as the sum ofAzPz-l-AaPH-S, in which A2 represents the area dened by the innerdiameter of the cylindrical member 31, P2 the pressure acting withincham- ,ber 33, A3 the diierence between the areas A1 andv 'A2, Pathepressure within the outlet, and S the biasing force of the spring. Foropen position o f the valve we have then the following equation:

'Forour present consideration we may assume the factors P1, P3 to remainconstant and S to increase in proportion to the opening travel of theValve.` The only variable on the left side of the equation is then fandthe only variable on the j right side of the equation is P2. This,however, 'means that we have vto change P2 in accordance with the changeofthe ilow factor f to obtain thedesired regulation, or, from anotherviewpoint, we have to decrease the magnitude of iAzPz` in accordancewith the vdecrease of the magnitudeAV of A1P1f with the movable memv bermoving away from' its seat. This is accomplished with the arrangementshown in Fig. 1 by the chamber 33 which may be termed a pressure chamberdefined between lthe vmovable member and the stem. The pressure Pzwithinthe chamber is equal to the pressure P1IP2=P11 to be relieved as long asthe movable member engages its seat (Fig. 2). 'Ihe pressure P2 issmaller than P1[P2 P1l if the movable member is moved away from itsseat, asshown in Fig. 3, because the pressure Prat the entranceY to theopenings 34 has decreased, the pressure P2 within chamber 33 beingsubstantially equal to the pressure eX- isting at the entrance of theopenings 34. The

Vrelative decrease of the pressure P2 depends upon vthe location of theentrances of the openings 34. ,',Th'e closer these entrances areVlocated to the seat of the valvethe greater will be Ythe decrease ofthe` pressure P; for any position of disk 30 and the closer theentrances are located to the center ofthe valve the less willrbe thedecrease with regard to the arrangement in Fig. 1, and

Vmember for different valve opening` positions.

"The essence of the invention as brought out 4above comprises theprovision of means for biasing the'movable member toward its seat with aforce: decreasing in accordance with the decrease of the force A1P1f;This'decrease whichis equal A1P1 lf) is represented by curve. III. The

three forces acting on the upper side of the mov- 'able member arerepresented individually bythe curves IV, V and VI; of which the curveIV represents the force A zPz exerted by the pressure in chamber 30,AaPa represents the force exerted by the pressure P3 in theoutlet of thevalve, which in the presentinstance--has been assumed to remainconstant, and VI represents therforce Sexerted by the spring which hasbeen assumed to increase in proportion with the opening travelA of thevalve. The Vcurve VII represents the sum of the three forces which inany position of the movable member is equal to the corresponding 10 f'product A'1P1f.- A valve with this characteristic has zero regulationwhich means that the pressure P1 is independent of the opening travelofthe valve. With the proper proportioning of the pressure chamber 33 andthe openings leading theretoI may obtain a relief valve withnegativeregulation, that is, one in which thepressure P1 to be relieved;decreases as the moVable'nember4 is moved further away from its seat'. YThisisacz complshed by 'an arrangement in which the force 20 A2P2represented by curve IV in Fig. 5 decreases faster than shown in Fig. 5.Y. l In-Fig. 6, where I have shown a modified arrangement according tomy invention, the `Valve comprises a casing 40 havingA afiian'ged'portion gigs defining anV inlet and being fastened toal con",Y tainer 41 for containing fluid under Vpressure -to be relieved whenthe pressure reachesV` and exceeds apredeterminedvalue. Anannular'rnem-l ber 42 is welded to the inlet of the YVcasing"and5,0v

defines a seat. A movable Y-merr'iber 43 slid-f ably arranged on a fixedstem44 corresponding Y to stem 21 in Fig.r1 and biased towards itsjseatby a spring 45 corresponding to spring "3 5 in Fig.

1. The movable member andthe stem define'a5 i chamber 46 whichcommunicates'with the inlet of the valve lthrough an opening ,47u nearthe center of the valve disk. The Ylower endofthe stem has a centralbore v48 and an outer recess'49 communicating with the bore 48throughanopcnA- 40 ing 50. `The cylindrical member has anfopening 39which in the closed position of' the valv'e is located below Ytheannular recess4 49. 'I'he pressure within the chamber 46 is equalto thepressure to be relievedas long as the valve is K .Y closed. If the valveis opened and moves away from its .seat the opening 39'registers'graduallyV with the annular recess`49 and permits iluid to bedischarged from the `chamberj46 through the bore 48, opening 50,recess49'and opening 39550. v'

into the outlet of the valve."4 The dischargedlfluid is replaced by iuidsupplied from theiinletjside of the valve. Thefflow of iiuid through;chamber 46 causes a conversion of potentialy energy into K velocityenergy, to the effect that thepressure inf55 this chamber ldecreases asthe valve is vmoved'. further away from its seat. lThe operation ofthevalve in this respect is the same v4as, that-ofv the valve in Fig. 1.,The relative decrease of the bias-"g ing force depends upon thedimensions of 'theva-tfo .v

rious openings, particularly the dimensionl of the openings 47, 50 and39; 'Ihe dimensions of thesev openings determine the resistance to therflow of. fluid through the pressure Vchamber and ,accord-s ingly thepressure `within Vsaid chambenj -Acf cording to the change of thisresistancethefvalve has either zero regulation or a negativeV oraLl-positive regulation. y f 1 In Fig. 7 I have shown an arrangementwhichM permits adjustment 'of rthe regulation bychang-m/0 A ing theresistance to the"Ilowfofriluid through oneY of said channels.V Thearrangement comprises a movable valvemember 51 corresponding to member43 of Fig. 6,` an annular'memben 52,...

dening a valve seat corresponding to'v the'mel. Y

CII

ber 42 of Fig. 6 and a'hollow valve stem 53 corresponding to the hollowstem 21 of Fig. 1. The

movable member 51 is biased towards closing position by a spring 54. Themovable valve member and the stein define a chamber 55 whichcommunicates with the inlet side of the valve through an opening 56 inthe valve disk. 'Ihe valve stem 53 has an annular recess 57corresponding to the recess 49 in Fig. 6 and an opening 58 correspondingto the opening 50 in Fig. 6 for permitting communication between thespace dened by the recess and the pressure chamber 55. The movable valvemember 51 has an opening 59 which gradually registers with the recess 57in thestem as the movable valve member moves upward to permit ilow ofiuid from the pressure chamber into the outlet of the valve. In order topermit adjustment of the valve regulation I provide a pin 60 slidablyarranged in the bore of the valve stem 53. The lower end of the pin hasa cut-off portion 61 adjacent the openingV 58. The upper end ofthe pinmay be arranged similarly to the arrangement of the pin 36 in Fig. 1.The flow through the opening 58 is adjusted byturning the pin 60 wherebythe cut-olf portion 61 registers with a portion of the hole 58 andincreases the resistance to the ow of iuid therethrough. In the positionindicated in the drawing the resistance is a minimum and the flow ofVfluid through the pressure chamber accordingly a maximum. In thisposition we may assume that the valve has a negative regulation. If theopening 58 is partly shut by turning the pin 60, the flow decreases andin a certain position of the pin the valve has no regulation. If the pinis further turned, that is, the iiow through the pressure chamberfurther decreased, the regulation or the valve becomes positive.

With my invention I have accomplished a simple and reliable constructionfor a relief valve in which the regulation of the valve may be adjusted.The arrangement is particularly important where the increase of the uidpressure in a container beyond a definite value has to be prevented. y

Another important feature of my invention is the elimination ofvibrations of the movable valve member during fluctuationsl of the fluidpressure, particularly when the movable member is moved slightly awayfrom its seat. The movable member with the pressure chamber behind'itacts like a dashpot to take up or dampen the vibrations of the valvecaused by sudden changes in uid pressure. This eliminates undesirablenoise during the relief valve operation.

Having described the method of operation of my invention, together withthe apparatus which I now consider to represent the best embodimentsthereof, I desire to have it understood that the apparatus shown is onlyillustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a relief valve structure, the combination of a casing defining aninlet, an outlet and a seat, a movable valve member, and uid pressureactuated means for biasing the movable valve member towards theseat-with a force decreasing in response to the opening travel of themovable member, said means comprising a chamber communicating with theinlet in closing position of the valve.

2. In a relief valve structure, the combination of a casing defining aninlet, an outlet and a seat, a stem fastened to the casing, a valvemember slidably arranged on the stem and defining a chamber therewithcommunicating near the edges of the seat with the inlet of the valve,and a spring for biasing the valve member against the seat.

3. In a relief valve structure, the combination of a casing defining aninlet, an outlet and a seat, a stem fastened to the casing, a Valvemember slidably varranged on the stem and defining a chamber therewith,a spring for biasing the valve member towards the seat, the memberhaving openings for permitting fluid under pressure being conducted tothe chamber and for relieving the pressure within the chamber inresponse to opening travel of the movable member.

4. In a relief valve structure, the combination of a casing defining anvinlet, an outlet and a seat, a stern fastened to the casing, a movablevalve member having a cylindrical portion sliding on the stern and adisk united with the cylindrical portion dening a chamber, and meansVfor biasing the disk towards the seat comprising a spring and uid underpressure forced into-the chamber with a pressure decreasing in responseto the opening travel of the valve.

5. In a relief valve structure, the combinatie of a casing defining aninlet, an outlet and a seat, a'stem fastened to the casing, a movablevalve Vmember slidably arranged on the stein and defining a chambercommunicating through an opening in the wall of the member with theinlet side of the valve, a spring for biasing theV of the casing, springmeans for biasing the movable member towards its seat, a lateral openingin the movable member located below the lateral opening in the stem atclosed position of the valve and permitting uid to flow from the inletthrough the chamber into the outlet as the valve is opened whereby theforce biasing the valve towards its seat decreases, and means forcontrolling the flow through the chamber comprising a pin having acut-off end portion inserted in the axial bore of the stem.

R. WAYNE McLAUGI-ILIN.

ioY

